Cheapest priced copy (The List): $0.35 at Card Kingdom, near mint, their price list as of .
Eutropia the Twice-Favored 
Legendary Creature — Human Wizard · 2/2 · Uncommon · Theros Beyond Death · #216
Constellation — Whenever an enchantment you control enters, put a +1/+1 counter on target creature. That creature gains flying until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | THB-216 | Uncommon | $0.35 | — |
| Theros Beyond Death | 216 | Uncommon | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 24 January 2020If an enchantment creature enters the battlefield under your control, Eutropia’s ability can target that creature.
- 24 January 2020An Aura spell that has an illegal target when it tries to resolve doesn’t resolve and is instead put into its owner’s graveyard. It doesn’t enter the battlefield, so constellation abilities don’t trigger.
- 24 January 2020Eutropia can be the target of its own triggered ability.
- 24 January 2020A constellation ability triggers whenever an enchantment enters the battlefield under your control for any reason. Enchantments with other card types, such as enchantment creatures, will also cause constellation abilities to trigger.
- 24 January 2020Eutropia’s ability can target a creature that already has flying. It still gets a +1/+1 counter. Multiple instances of flying on the same creature are redundant.